i got a couple of questions on leeway. i''m not sure if this term is correct, i''m talking about the sideways drift of the boat while sailing.

First, is there any way to compute that value? i have heard that if you want to go for example from point A to point B, the fastest way is not to point the boat directly to point B, but a little towards windward. Is this true? If so, how can you assess how much exactly to compensate. Is there any rule? or just experience?

Also, as a beginner i get contradicting oppinions on how much a sailboat can lean sideways witout loosing speed (both absolute speed and speed with reference to the destination including drifting)

I got people telling me that up to 40 degrees is OK, but other insist that you should reduce sail if you get that kind of leaning and you''d be going faster.

Ben, the traditional answer about leeway is that it''s just experience, since various designs of boat may have different rates of "sideslip" or leeway. It varies too depending on what point of sail you''re on (more leeway sailing close-hauled than on a broad reach, for example), wind strength, height and type of seas, and how much you''re heeling. On a passage of some length, you might head, say, 5 degrees above the charted course and see how it goes.

The "modern" answer, if you have GPS, might be to compare your GPS course-made-good to your course steered. The difference (assuming there''s no current) would be your boat''s leeway.

As to leaning sideway ("heeling") most boats are designed to heel about 10-15 degrees for maximum speed sailing upwind. At 20-25 degees, it''s time to reduce sail. 40 degrees is extreme, any sailboat heeling that far is carrying way too much sail and is overpowered.

Excessive heeling also creates excessive leeway, as the hull and keel become less efficient at resisting sideslip when they become less "vertical" during excessive heeling.

Also with most keelboats your cross track error, (that is where you go as compared to where you pointed), is affected more by currents, helmsman deviation and compass error than by leeway from the boat sliding sideways. Usually when piloting most people lump all this deviation together & call it leeway or XTE and so use it to correct their DR plot.

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